public class TestDemo {
    public static void main(String[] args) {
        String str="hello";
        System.out.println(str);
        //注意问题
        System.out.println("hello"+"world");//拼接
        System.out.println("hello"+10+20);
        System.out.println(10+20+"hello");
    }
    public static void main1(String[] args) {
        //System.out.println("hello");
        boolean flg=true;
        System.out.println(flg);
        boolean flg2=false;
        System.out.println(flg2);
    }
}
